Propeller driven and rotor wing aircraft moving through the atmosphere generate radio frequency emissions of various frequencies and intensities. Of these emissions, those in the 1000 MHz region appear to be the most consistent and are utilized by this invention. The use of this high frequency band in a detector also results in small circuit elements and a correspondingly miniature overall assembly.
It is thus an object of the invention to provide a useful, compact passive aircraft proximity detector for use in a highway vehicle, by which high frequency emissions in the 1000 MHz region radiated by surveillance aircraft can be detected and an appropriate signal of aircraft proximity can be generated to inform the vehicle operator of such aircraft.
Further objects of the invention are to provide such a detector operating within the frequency range of 900 to 1300 megahertz for use in highway vehicles. In addition, it is an object of the detector to incorporate an internal antenna within the detector itself and to provide further means of indicating that an aircraft has been detected.
A further object is to provide an aircraft proximity detector with an ability to determine and read out the approximate range of aircraft and to provide an audio alarm that is activated when an aircraft is within range. As an element of this object the detector may incorporate means to deactivate the audio alarm.
Similarly, it is an object also to provide an aircraft proximity detector having a user adjustable detection range.
The aircraft proximity detector is preferably powered by 12 volts DC, conventional to highway vehicles, and incorporates a power indicator, a means of turning the power on and off, and is formed in a microstrip structure, that incorporates a harmonically related local oscillator system.
These and further objects are evident from the following description taken in conjunction with the drawings in which: